In the oil and gas industries, coiled tubing refers to metal piping used for interventions in oil and gas wells and sometimes as production tubing in depleted gas wells. Available in sizes ranging from 1 inch to 4.5 inches, coiled tubing strings are carried on reels and injected into a wellbore using a coiled tubing injector unit. A typical coiled tubing injector unit 5 is illustrated in FIG. 1. The typical unit includes a goose-neck support 3, a rotary transmission assembly, parallel drive chains 7 carrying gripping insert assemblies, skates and a hydraulic system. (The transmission assembly, gripping insert assemblies, skates and hydraulic system are not shown in detail in FIG. 1). Those skilled in the art are familiar with the components and operation of the unit 5 illustrated in FIG. 1.
The series of gripping insert assemblies carried by the chains provide the sole direct support for holding the coiled tubing in place or moving the tubing. The gripping insert assemblies are arranged in opposing pairs to secure the coiled tubing string between the injector-head chains. The hydraulic system applies pressure to the skates which in turn force the gripping insert assemblies toward each other thereby securing the coiled tubing between the gripping insert assemblies. Additionally, the hydraulic drive system drives the chains to feed the coiled tubing string into the well or pull the tubing out of the well.
A typical gripping insert assembly includes a carrier block secured to the drive chain and a gripping insert supported by the carrier block. From time to time, the gripping insert must be replaced due to damage or wear or to accommodate a change in tubing diameter or insertion of a downhole tool. Thus, a need exists for a gripping insert assembly which permits quick replacement of the gripping insert.
In one aspect, embodiments disclosed herein relate to a coiled tubing injector unit insert assembly including a gripping insert configured to be coupled to a carrier block, the insert comprising a tongue with a first cutout configured to engage a shaft extending within a carrier block pocket, the shaft having a first diameter portion and a second larger diameter portion and a junction between the two shaft diameters that is located within the carrier block pocket to couple the gripping insert to the carrier block.
In other aspects, embodiments disclosed herein relate to a coiled tubing conveying apparatus including a pair of continuous parallel drive chains revolving in a common plane, said pair of continuous drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing there through, and a plurality of gripping insert assemblies carried on each of said pair of continuous drive chains, each comprising a gripping insert configured to be coupled to a carrier block, the insert comprising a tongue with a first cutout configured to engage a shaft extending within a carrier block pocket, the shaft having a first diameter portion and a second larger diameter portion and a junction between the two shaft diameters that is located within the carrier block pocket to couple the gripping insert to the carrier block.
In yet other aspects, embodiments disclosed herein relate to a method of assembling a coiled tubing injector unit insert assembly including providing a gripping insert configured to be coupled to a carrier block, the insert comprising a tongue with a first cutout configured to engage a shaft extending within a carrier block pocket, the shaft having a first diameter portion and a second larger diameter portion and a junction between the two shaft diameters that is located within the carrier block pocket to couple the gripping insert to the carrier block, inserting the gripping insert tongue into the carrier block pocket until the first cutout is substantially concentrically aligned with the larger shaft diameter portion, and sliding the gripping insert in a first direction and causing the first cutout in the tongue to engage the larger shaft diameter portion, thereby coupling the gripping insert to the carrier block.